The present invention relates generally to a side flow cooling device for removing heat from a component connected with the side flow cooling device. More specifically, the present invention relates to a side flow cooling device including a heat mass and a plurality of vertically oriented fins built around the heat mass. Heat in the heat mass spreads vertically into the fins. Cooling surfaces of the fins and a slot between the fins are aligned with a longitudinal axis of the heat mass so that an air flow for dissipating heat from the fins can be generated by an air flow source positioned at a side face of the side flow cooling device.
It is well known in the electronics art to place a heat sink in contact with an electronic device so that waste heat generated by operation of the electronic device is thermally transferred into the heat sink thereby cooling the electronic device. With the advent of high clock speed electronic devices such as microprocessors (xcexcP), digital signal processors (DSP), and application specific integrated circuits (ASIC), the amount of waste heat generated by those electronic devices and the operating temperature of those electronic devices are directly proportional to clock speed. Therefore, higher clock speeds result in increased waste heat generation which in turn increases the operating temperature of the electronic device. However, efficient operation of the electronic device requires that waste heat be continuously and effectively removed.
Heat sink devices came into common use as a preferred means for dissipating waste heat from electronic devices such as the types described above. In a typical application, a component to be cooled is carried by a connector that is mounted on a PC board. A heat sink is mounted on the component by attaching the heat sink to the connector using a clip or fasteners, for example. Alternatively, the heat sink is mounted to a PC board that carries the electronic device and fasteners or the like are used to connect the heat sink to the PC board via holes that are drilled in the PC board.
Typically, a heat sink used in conjunction with a modern high clock speed electronic device will use an electrical fan mounted on top of the heat sink or within a cavity formed by cooling fins/vanes of the heat sink. The cooling fins increase the surface area of the heat sink and maximize heat transfer from the heat sink to ambient air that surrounds the heat sink. The fan causes air to circulate over and around the cooling fins thereby transferring heat from the cooling fins into the ambient air.
As mentioned previously, with continuing increases in clock speed, the amount of waste heat generated by electronic devices has also increased. Accordingly, to adequately cool those electronic devices, larger heat sinks and/or larger fans are required. Increasing the size of the heat sink results in a greater thermal mass and a greater surface area from which the heat can be dissipated. Increases in fan size provide for more air flow through the cooling fins.
There are disadvantages to increased fan and heat sink size. First, if the size of the heat sink is increased in a vertical direction (i.e. in a direction transverse to the PC board), then the heat sink will be taller and may not fit within a vertical space in the system that carries the heat sink, such as the chassis of a desktop computer.
Second, if the PC board has a vertical orientation, then a heavy and tall heat sink can mechanically stress the PC board and/or the electronic device resulting in a device or PC board failure.
Third, a tall heat sink will require additional vertical clearance between the heat sink and a chassis the heat sink is contained in to allow for adequate air flow into or out of the fan.
Fourth, when the heat sink has a cylindrical shape formed by the fins it is often not possible to mount several such heat sinks in close proximity to each other because air flow into and out of the fins is blocked by adjacent heat sinks with a resulting decrease in cooling efficiency.
Finally, increases in fan size to increase cooling capacity often result in increased noise generation by the fan. In many applications such as the desktop computer or a portable computer, it is highly desirable to minimize noise generation. Moreover, in portable applications that depend on a battery to supply power, the increased power drain of a larger fan is not an acceptable solution for removing waste heat.
In the above mentioned heat sink with cooling fins there are additional disadvantages to mounting the fan within a cavity formed by the fins. First, a substantial portion of a heat mass of the heat sink is blocked by the fan because the fan is mounted directly on the heat mass and therefore blocks a potential path for heat dissipation from the heat mass because air from the fan does not circulate over the blocked portion of the heat mass.
Second, without the fan, a depth of the fins could extend all the way to a center of the heat mass; however, the depth and surface area of the fins is reduced by a diameter of the fan because the fan is mounted in a cavity having a diameter that is slightly larger than the fans diameter to provide clearance for the fans blades. Consequently, the heat mass of the heat sink must be made broader to compensate for the reduced surface area of the fins. The broader heat mass increases the size, cost, and weight of the heat sink.
Third, the reduced depth of the fins makes it easier for the fins to be bent if damaged. One possible consequence of a bent fin is that it will contact and damage the fan blades and/or cause the fan to stall thereby damaging the fan or causing the fan to fail.
Fourth, because the fan is mounted in the cavity formed by the fins, power leads for the fan must be routed through a space between the fins. Sharp edges on the fins can cut the power leads or cause an electrical short. In either case, the result is that the fan will fail.
Lastly, glue is typically used to mount the fan to the heat sink and the glue can get into the fan and cause the fan to fail. Any of the above mentioned fan failure modes can lead to a failure of the electronic device the heat sink was designed to cool because air circulation generated by the fan is essential to effectively dissipate waste heat from the electronic device.
Consequently, there exists a need for a cooling device that includes a heat mass having one or more surfaces that are populated with as many fins as possible so that a surface area available for removal of waste heat is maximized. There is also a need for a cooling device that includes a heat mass that is not blocked by a fan so that the number of fins connected with the heat mass can be increased and an air flow from the fan can pass over the heat mass and the fins to dissipate waste heat. Additionally, there exists a need for a cooling device with a central heat mass having fins aligned along a longitudinal axis thereof so that vertical clearance requirements are reduced. Finally, there is a need for a cooling device adapted for mounting a fan on a side of the cooling device so that an air flow from the fan passes over the fins and the heat mass of the cooling device along a longitudinal axis and so that air can easily enter and exit the fan.
Broadly, the present invention is embodied in a side flow cooling device for dissipating heat from a component. Typically, the component is an electronic component or an electronic device; however, the side flow cooling device of the present invention can be used in conjunction with any heat producing device and is not limited to use with electronic devices or components.
The side flow cooling device of the present invention includes a heat mass with a top surface, a mounting surface for thermally connecting the heat mass with the component to be cooled, opposed side surfaces, and opposed end surfaces. An arm extending outward of the opposed side surfaces includes an upper surface and a lower surface. A rib is connected with the arm an extends from the arm in a downward direction. A wing is connected with the rib and extends outward of the rib.
A plurality of fins are connected with the top surface of the heat mass and the upper and lower surfaces of the arm. The fins are aligned with a vertical axis of the heat mass such that they extend outward of the surfaces they are connected with and are aligned along the vertical axis. Each fin includes a top edge, opposed end edges, and opposed cooling surfaces. The opposed end edges define a first side face and a second side face of the side flow cooling device. The fins are spaced apart and the space between adjacent cooling surfaces defines a slot. The slot and the cooling surfaces are aligned with a longitudinal axis of the heat mass.
An air flow entering either of the first or second side faces in a direction that is substantially along the longitudinal axis passes through the slots and over the cooling surfaces of the fins and over the heat mass to dissipate heat from the heat mass.
An air flow source such as a fan, for example, can be mounted to either one or both of the first and second side faces to generate the air flow. Because the air flow source is mounted horizontally with the side flow cooling device, the problems associated with vertically mounted fans are solved by the present invention. Furthermore, by side mounting the air flow source, air can easily enter and exit the air flow source without being blocked or otherwise obstructed by a chassis, other cooling devices, other components, or the like.
Another advantage to side mounting the air flow source is that two or more air flow sources can be mounted to the first and second side faces to either increase air flow, to provide redundancy in the event of failure of one or more of the air flow sources, or to provide a push-pull air flow wherein one air flow source pushes the air flow through the slots between the fins and another air flow source pulls the air flow through the slots.
Moreover, because the air flow source is side mounted, the heat mass is not blocked by the air flow source. Therefore, the number of fins in contact with the heat mass can be increased with a resulting increase in heat transfer from the heat mass into the fins.
Additionally, the surface area of the heat mass that is not covered by the fins is open to the air flow so that the air flow can pass over the heat mass and dissipate heat therefrom.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention.